Republican presidential frontrunner Donald Trump offered a full-throated defense of his embattled campaign manager late Tuesday afternoon, saying he won't allow Corey Lewandowski's life to be "destroyed" by a battery charge stemming from a physical run-in with a reporter.

Speaking to reporters as his plane sat on the tarmac in Janesville, Wisconsin, Trump accused former Breitbart reporter Michelle Fields of grabbing him first. He argued Lewandowski was just trying to make room after a press conference when he allegedly grabbed Fields hard enough to leave a bruise.

Calling the misdemeanor charges against Lewandowski in Florida "very unfair," Trump also suggested Fields changed her story after realizing there was video of the incident.

"If you look at her initial statements, before she knew that we had tapes of her, she was talking about being pulled down or dragged down or something to that effect," he told reporters. "And all of a sudden, when she saw that there were tapes, she changed her tone a little bit."

Asked about Fields' tweeting a photo of finger-shaped bruises on her arm, which she said she sustained during the incident, Trump wondered why she didn't scream if Lewandowski hurt her.

"How do you know those bruises weren’t there before? I’m not a lawyer," he said. "To me, if you're going to get squeezed, wouldn't you think she would have yelled out a scream or something if she has bruises on her arm?"

Trump also repeatedly said his campaign manager has "four beautiful children" back home in New Hampshire and called him a "good person."

"I think it's very, very unfair to a man with a wonderful family, back in new Hampshire, who gets, what, a criminal situation, over that?" the billionaire exclaimed. "I think it's a very, very sad day in this country when a man can be destroyed over something like that."

He went on: "And she was grabbing me. Does that mean that I'm supposed to file charges against her? She was grabbing me...Because to be honest with you, the news conference had finished. It was over. It was done."

Trump said he advised Lewandowski to "never settle" the Florida case. Earlier Tuesday afternoon, national campaign spokeswoman Katrina Pierson said Lewandowski would stay on the campaign even if he was convicted of battery.

"I don't discard people, I stay with people," Trump said of his top aide.